Trailer bodies are typically provided with a pair of side-by-side swing doors for closing an open rear end of the trailer body. Each swing door is pivotally interconnected to the trailer body by a plurality of vertically spaced hinges which are typically made of metal. Each hinge is configured to permit the swing door to move through an arc of about 270.degree.. The door to which the hinge is connected is typically formed from wood with a steel or aluminum sheeting on the inner and outer sides thereof.
As is well known, a series of fasteners, i.e., threaded bolts and nuts, are used to secure each hinge to a swing door. Because they are secured outside of the trailer body and door, the metal hinges are exposed to all environmental conditions such as rain, sleet, snow as well as road salts, greases and oils. As will be appreciated, a metallic hinge performs poorly in the early stages of corrosion and can become completely inoperable if the corrosion is not stopped. To reduce the likelihood of corrosion, a Mylar backing is usually positioned between each hinge and the door.
After arriving at a delivery site, it is common to swing open each of the doors, at the rear of the trailer body, from their closed position through an arc of about 270.degree. and secure them to the sides of the trailer body. Thereafter, the trailer body is driven rearwardly and positioned relative to an unloading area which, typically, includes a raised dock.
Occasionally, the doors are not properly secured to the sides of the truck or trailer body and, as the trailer body is moved rearwardly, the doors tend to swing away from the side of the trailer body toward a partially closed position. Unfortunately, the driver does not always realize, or is not always alerted to, the door at the rear of the trailer body becoming unfastened from the side. Eventually, and as a result of the continued rearward movement of the trailer body, the partially closed door is jammed against the dock which can result in significant damages to the door and/or the trailer body.
Even when the doors remain fastened to the side of the trailer body, space constraints in some dock areas is extremely limited. Accordingly, and as the trailer body is being moved rearwardly into position relative to the dock, it is not uncommon for the door to engage or snag an adjacent trailer body. Here again, excessive forces are applied in a longitudinal direction to the hinges connecting the doors to the trailer body. As mentioned above, such excessive shear forces can result in significant damage to either or both the trailer bodies. That is, the trailer body and/or the swing door on one or both of the trailers can be damaged.
As mentioned above, swing doors for closing the rear open end of trailer bodies and the like are typically connected to the trailer body with a plurality of vertically spaced hinges. Thus, when the door is jammed against a dock or adjacent trailer body, the resulting damage to the door usually requires repair and/or replacement of more than one of the hinges. This is a time consuming repair operation usually involving extensive manual efforts, thus, resulting in costly repairs. Of course, during the repair, the trailer body is removed from service, thus, adding to the overall costs involved in effecting door repair and/or replacement.
Thus, there is a need and desire for a hinge structure which will connect the swing door to a trailer body or the like in a manner permitting movement of the swing doors through an arc of about 270.degree. while conjointly inhibiting damage to the door and trailer body when shear forces exceeding a predetermined magnitude are applied to the hinge.